This invention concerns a multibeam antenna which has a high switching capability with high RF power levels. It relates to the field of electronically switched beam antennas. The invention may find application in the field of electronic defence systems by handling single or multiple threats arriving from different directions.
The antenna can provide pseudo adaptability to the radar cross section, as it is made up of three subarrays, each of which includes eight elementary equispaced radiators which assure angular coverage of the azimuth hemispace from 0.degree. to 180.degree., fed by a single beamshaping network which provides the correct field amplitude and phase distribution.
The hemispace is therefore divided into-three angular sectors, with each of which a subarray is associated. Switching between these angular sectors and within each sector is electronic.
Each subarray, as mentioned above, shapes three beams which take different angular positions on the azimuth plane through the same feed network. The selection of these beams is electronic upon designation by the system which assesses relevant direction of arrival. One of the previous solutions was to utilize arrays fed by Rothman lenses or by Butler matrixes. Another solution was provided by a series of directional antennas, one for each beam to shape, fed by an n-way switch (as many ways as the number of beams) or by transmitters.
These solutions have a number of drawbacks, among them:
proliferation of the number of transmitters, with consequential cost and dimension increase; PA1 low switching speed, for the switching network, due to the high RF levels involved. PA1 high switching times with high total RF power radiated; PA1 high effective radiated power associated with each single beam; PA1 azimuth coverage over the whole round angle using two radiating systems, each having a 0.degree. to 180.degree. coverage sector; PA1 capability to adapt to the number of beams of the designating system.